What is the difference between a function and a method in programming?

A function is a standalone block of code, while a method is associated with an object and can access that object's data.

In programming, both functions and methods are reusable blocks of code that perform a specific task. However, they are used in different contexts and have different access to data. A function is a standalone entity that can take input, perform computations, and return output. It is defined outside of classes in procedural programming languages like C and can be called independently. Functions are also used in functional programming languages like Haskell, where they are the primary means of building and structuring software.

On the other hand, a method is a function that is associated with an object in object-oriented programming (OOP). Methods are defined within classes and are used to manipulate the data contained within the object they belong to. They can access and modify the data members of the class they are defined in, which is not possible for standalone functions. Methods are used in OOP languages like Java, Python, and C++.

The key difference between a function and a method lies in the concept of 'state'. A function does not have a state, as it only operates on the inputs provided to it and does not retain any information between calls. However, a method can have a state because it is associated with an object and can access and modify that object's data. This means that the behaviour of a method can change based on the state of the object it belongs to.

In summary, while functions and methods both perform computations, they are used in different programming paradigms and have different levels of access to data. Functions are standalone entities used in procedural and functional programming, while methods are associated with objects and used in object-oriented programming.